Thiazyl-dithiocarbamates



Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE No Drawing.Application November 14, 1934, Serial No. 752,988

9 Claims.

This invention relates to a new and useful class of chemical compoundsand to a method of preparing them. More particularly, it concerns aclass of materials which may be termed thiazyl esters of dithiocarbamicacids derived from secondary amines containing a hydrogenated furanering. Although these compounds may perhaps be prepared by other methodsas Well, they are preferably formed by reacting a suitable salt of adithiocarbamic acid derived from secondary amines containing ahydrogenated iurane ring with a halogen aryl thiazole, While thecompounds of the invention may be used for any purpose for which theyare suited, it has been found that they are in general good acceleratorsof rubber vulcanization.

Although any halogen aryl thiazole may be employed, it has been foundthat the l-chlor aryl thiazoles are particularly well adapted for thepurposes of the invention. Of the l-chlor aryl thiazoles, l-chlor5-nitro benzothiazole in particular has been found to give rise toproducts which are excellent accelerators of the vulcanization ofrubher. It will, of course, be understood that other halogen arylthiazoles may be employed in the practice of the invention, examplesbeing l-chlor 5-methoxy benzothiazole, l-chlor benzothiazole,

l-chlor tolyl thiazole, l-chlor 4-nitro benzothiazole, l-chlor 5-ethoxybenzothiazole, l-chlor 5- 30 methyl benzothiazole, l-chlor dimethylbenzothiazoles, l-chlor 4- or 5-chlor benzothiazole, 1- chlor 3-phenylbenzothiazole, l-chlor naphtho thiazoles and their nitro derivatives,l-chlor 4- chlor 5-nitro benzothiazole and l-chlor B-methyl 5-nitrobenzothiazole, These halogen aryl thiazoles may conveniently be preparedby the process disclosed in United States Patent No. 1,757,- 930.

The dithiocarbamates used in this process may 40 be represented by theformula 45 wherein R represents a radical containing a hydrogenatedfurane ring such as tetrahydro furfuryl; R1 is any monovalent organicradical, alicyclic, aralykyl and alkyl radicals being typical; and M isany reactive metallic radical or equiva- 50 lent group, such as sodium,potassium or ammonium, which does not seriously impair the solubility ofthe dithiocarbamate in the solvent employed in effecting the desiredreaction.

These dithiocarbamates are prepared by known 55 methods from secondaryhydrogenated furyl amines. Amines containing a, hydrogenated furane ringare generally and most easily prepared by hydrogenation processes andare those amines in which the double bonds of the furane ring aresaturated, fully or partially. While the sec- 5 ondarytetrahydrofurfuryl amines are the preferred class of amines applicablefor use in the practice of the invention, it will be understood that theinvention extends to the partially saturated amines such as the dihydrofuryl amines, 10 which, while not generally preparable by hydrogenationprocesses, may be obtained by synthesis.

For the purposes of simplicity the term secondary amines containing ahydrogenated furane ring is used herein to refer to those amines con- 15taining a fully or partially saturated furane ring, however prepared. Ingeneral, any secondary amine containing a hydrogenated furane ring andin which aliphatic characteristics predominate may be employed in thepractice of the in- 0 vention.

Illustrative of salts of dithiocarbamates which may be employed in theinvention are potassium di(tetrahydro alpha furfuryl) dithiocarbamate,sodium di(tetrahydro alpha furfuryl) dithiocarbamate, ammoniumN-cyclohexyl tetrahydro alpha furfuryl dithiocarbamate, sodium N- ethyltetrahydro alpha furfuryl dithiocarbamate, sodium p-methoxy cyclohexyltetrahydro alpha furfuryl dithiocarbamate, potassium isopropyltetrahydro alpha iurfuryl dithiocarbamate, sodium methyl tetrahydroalpha furyl dithiocarbamate, potassium phenyl tetrahydro-alpha furfuryldithiocarbamate, sodium isobutyl tetrahydro alpha furfuryldithiocarbamate, ammonium n-propyl tetrahydro alpha furfuryldithiocarbamate, sodium tetrahydro furfuryl methyl dithiocarbamate,ammonium isoamyl tetrahydro alpha furfuryl dithiocarbamate, sodiumtetrahydro furfuryl benzyl dithiocarbamate, sodium di(2-tetrahydro alphafuryl ethyl) dithiocarbamate, ammonium di(tetrahydro alpha furyl)dithiocarbamate, ammonium n-butyl tetrahydro furfuryl dithiocarbamate,sodium deca hydro naphthyl tetrahydro furfuryl dithiocarbamate, sodiumbeta phenyl ethylene tetrahydro furfuryl dithiocarbamate and potassiumhexahydro tolyl tetrahydro furfuryl dithiocarbamate.

The desired halogen aryl thiazole may be caused to react with anydithiocarbamate derived from a secondary amine containing a hydrogenatedfurane ring to produce the corresponding reaction product. Although itis not known to be true in all cases, it is believed that the reactionproceeds according to the following general equation:

In certain cases other reactions may take place to the extent of perhaps30%, yielding products which may or may not be separated, as desired,from the main product. If desired, the total composite product may beemployed as such, as for example, as an accelerator of rubbervulcanization.

The reaction product of l-chlor -nitro benzothiazole and the sodium saltof di(tetrahydro alpha furfuryl) dithiocarbamate is an example of acompound falling within the scope of the invention. It may be preparedby refluxing l-chlor 5-nitro benzothiazole, di tetrahydro alpha furfurylamine, carbon bisulphide and an alkali such as sodium hydroxide in asolvent such as ethyl alcohol. After a period of from one half hour tofour hours the reaction product precipitates as a crystalline materialwhich may be washed with water to remove the sodium chloride formedduring the reaction. The crystalline material, 5- nitro benzothioazyl1-di(tetrahydro alpha furfuryl) dithiocarbamate, upon being furtherpurified by crystallizing from alcohol, precipitates in the form ofcream colored crystals having a melting point of 116-118 degrees C. Theproduct upon analysis is found to contain 9.38% nitrogen and 21.51%sulphur as compared with the theoretical percentages for 5-nitrobenzothiazyl 1- di tetrahydro alpha furfuryl) dithiocarbamate of 9.58%nitrogen and 21.89% sulphur. The equation representing the reaction isprobably as follows:

OzN- S, o

It will be understood that the dithiocarbamate derived from a secondaryamine containing a hydrogenated furane ring may be formed separately andreacted with the halogen aryl thiazole.

It is believed that by the practice of the invention any aryl thiazylester of a dithiocarbamic acid derived from a secondary amine containinga hydrogenated furane ring may be prepared without regard to the natureof the substituents in the aryl ring or to their position therein.However, the halogen nitro benzothiazoles have been found to be capableof being employed in the invention somewhat more conveniently thancertain of the other thiazoles, the presence of the nitro groupapparently facilitating the reaction. It will be understood that thebrom aryl thiazoles and other halogen aryl thiazoles may be substitutedfor the chlor benzo' thiazoles.v Similarly, the halogen naphthothiazolesmay be substituted for the halogen benzothiazoles.

Conveniently any of these new accelerators or a mixture thereof may beadded to any of the ordinary rubber mixes in an amount which may bedetermined according to the usual methods. It has been found for examplethat the compounds of thepresent invention are excellent CIT-OH;

delayed action accelerators in a rubber composition of the followingformula:

Parts by weight Extracted pale crepe 100 Zinc oxide 5 Sulphur 3 Stearicacid 1.5 Accelerator 0.5

Samples of the compounded rubber made up in accordance with this formulawere subjected to vulcanization by steam heat in a mold after which theywere subjected to physical tests to ascertain their elasticity andtensile strength.

The results of these tests are given in the following table.

5 -nitroben2othiazyl 1 -di (tetrahydroalphafurjuryl) dithiocarbamateCure m mt tenqfle Max. Modulus in kgs/cln mins. F in kgs/cm fi g 20/260No cure It will be understood that by the term rubber is meant any ofthe ordinary forms of rubber such as latex, balata, gutta percha,reclaimed rubber, and the ordinary coagulated forms of the HeveaBrasiliensis tree. It is intended that the patent shall cover, bysuitable expression in the appended claims, whatever features ofpatentable novelty reside in the invention.

This application is in part a continuation of application Serial No.720,100, filed April 11,

furfuryl dithiocarbamic acid prepared from a tetrahydro furfurylsecondary amine.

4. A compound having the formula S R: 5 S

c-s- N N/ R1 wherein R1 is a radical selected from the group 10consisting of tetrahydro furyl, tetrahydro furfuryl and beta tetrahydrofuryl ethyl radicals, and R2 is hydrocarbon.

5. A compound having the formula wherein R is an ortho arylene group ofthe henzene and naphthalene series, R1 is a tetrahydro alpha furfurylradical and R2 is an aliphatic hydrocarbon radical.

6. The 5-nitro benzothiazole ester of a di (tetrahydro furyl)dithiocarbamic acid.

7. A benzothiazyl ester of a tetrahydro fur-- furyl dithiocarbamic acidprepared from a tetrahydro furfuryl secondary amine.

8. A nitro benzothiazyl ester of di tetrahydro alpha furfuryldithiocarbamic acid.

9. 5-nitro benzothiazyl l-di (tetrahydro alpha furfuryD dithiocarbamate.

HOWARD I. CRAMER.

